update docker instructions and add some notes about using podman

also clean up some extraneous trailing whitespace

Signed-off-by: Chad Dougherty <[email protected]>

Author: Chad Dougherty

docs/local_previews.md

@@ -1,10 +1,10 @@
 # Working with the repo locally
 
-Content-only changes can often be done directly on the GitHub website.  Changes affecting the function or structure of the site should be previewed fully locally before being submitted via PR.  
+Content-only changes can often be done directly on the GitHub website.  Changes affecting the function or structure of the site should be previewed fully locally before being submitted via PR.
 
 ## Jekyll
 
-To preview the site locally, clone it.  
+To preview the site locally, clone it.
 
 Then you'll need to [install jekyll](https://jekyllrb.com/docs/installation/).
 
@@ -14,9 +14,9 @@ Then go to the root of the site and issue (just once):
 $ bundle install
 ```
 
-which will install the necessary Ruby gems (the info for this is included in the repo files).  
+which will install the necessary Ruby gems (the info for this is included in the repo files).
 
-And then (also in the top level directory of your forked repository) to be able to see the rendered website, run 
+And then (also in the top level directory of your forked repository) to be able to see the rendered website, run
 
 ```bash
 $ jekyll serve
@@ -32,6 +32,8 @@ If you are having trouble try `rm -rf _site`, followed by `bundle update`, then
 
 You can build and run a Docker container to preview the site locally and support a local development workflow. If you do not already have Docker installed, please visit https://docs.docker.com/get-docker/ and follow the links to get started with Docker on your operating system.
 
+These instructions also work with the [Podman](https://podman.io/) container management tool simply by substituting `podman` for `docker` in the commands below.  This can either be done manually, by creating a shell alias (e.g., `alias podman=docker`), or by installing a package such as `podman-docker` to automatically handle this translation.
+
 Build the container image:
 
 ```bash
@@ -59,9 +61,21 @@ To develop the website, launch the container using the following command, where
 
 ```bash
 docker run --rm -it -p 4000:4000 \
-    -v $(pwd):/srv/jekyll \
+    -u $(id -u):$(id -g) \
+    -v $(pwd):/srv/jekyll:Z \
     us-rse-website:latest
 ```
 
+or, if using Podman in a rootless environment:
+
+```bash
+podman run --rm -it -p 4000:4000 \
+    --userns=keep-id \
+    -v $(pwd):/srv/jekyll:Z \
+    us-rse-website:latest
+```
+
+If these commands fail, you may need to address any discrepancies between the user/group mapping in your container runtime and the permissions on the directory where the volume mount resides.
+
 Edit a source file and save the changes. You will see Jekyll automatically regenerate the site, after which you can reload the page in your browser to see the rendered changes.